1. Field of the Invention
The present invention relates to an ophthalmic apparatus, and more particularly to the ophthalmic apparatus for starting measurement by positioning the apparatus at a predetermined positional relation to an eye to be examined.
2. Description of Related Art
Regarding ophthalmic apparatuses such as an ophthalmic apparatus for measuring a refractive power of an eye to be examined or an ophthalmic apparatus for measuring a corneal curvature, after an alignment adjustment of measurement optical system of the apparatus to the eye is performed, a trigger signal for starting measurement is inputted so as to start measurement. Further, another apparatus has been proposed such as it provides a detecting mechanism for detecting an alignment condition, also measurement is to be started by automatically generating trigger signal when it is judged that an alignment condition is under a predetermined condition level.
Incidentally, another ophthalmic apparatus such as an ophthalmic apparatus for measuring a refractive power of an eye have a disadvantage that some alignment displacement can be caused during measurement, because it takes times to complete measurement after the trigger signal is generated, and therefore it may be possible that an apparatus will be shifted or the eye will be moved unexpectedly. In this case, such an obtained measured result tends to be improper. However, since there may be another case that an operator cannot realize that alignment displacement has been caused during measurement, it resulted in another disadvantage that some improper measured result were selected.
Generally, a plural measurements of the same eye are repeated in order to take process for obtaining its average value or central value as a measured result. Therefore, in case of an apparatus having means for automatically starting measurement, a continuous measurement has to be carried out until predetermined measurement times are achieved. Among these sort of ophthalmic apparatuses, it has been proposed that an apparatus comprises a TV monitor for observation to display which direction the apparatus should be shifted.
However, in case that such a continues measurement is performed for measurements of predetermined times, it may result in another disadvantage that a switch for separately starting measurement should be pressed, if it is necessary for the same eye to be measured once again after the continues measurement is completed. Although it has been set that measurement can be started automatically, the apparatus used to be necessary to equip with an optional switch for starting measurement. As a switch for starting measurement, the apparatus is generally equipped with a joystick in order to shift an apparatus opposite to an eye to be examined by the operator, but connecting of the joystick with electrical wire may cause some troubles such as break.
In addition, alignment adjustment has a following disadvantage. It had been much desirable to distinguish a direction indication that the apparatus should be moved by handling the joystick during alignment adjustment, especially for even operators who do not accustom himself to use an apparatus, the apparatus may be desirable to distinguish a directional indication that the apparatus should be shifted by handling the joystick.